Mitutoyo 519-807 Electronic indicator, needle not responding

Hello,

Received this unit and 1 probe with other tooling recently. The indicator lights respond with probe input but the needle does not zero on power-up or respond to probe.

Anyone have a similar problem that they were able to fix?

Thanks,

Bill

I bought a federal 130 of ebay this past winter for a song. I spent perhaps three whole days playing with the tuning pots to re-calibrate it. Got all but the 2 uin setting working. 5 uin isn't bad.

With the devicese reenergized the needle should read zero. For the purely analogue types of gauge amplifier the display is a galvanometer, and there should be a screw hidden in the enclosure or metal tabs to adjust the two hair springs in the gauge.

Analog meters should read dead on zero after the unit has been OFF for a few days.

To re-inforce this, you can twist some bare copper wire around the meter posts a few times.

If it is not zero, there is a small screw at lower front of the meter face to adjust it.

Once adjusted properly, move the screw back a hair to remove pressure from it on the mechanism.

-----

The most common problem by far in vintage electronics (over 10 years old) is bad electrolytics.

These are capacitors that are commonly used in the power supply and elsewhere.

They should be replaced with modern parts of equal rating.
The new caps should be close to the original capacitance, like 22mfd for an old 20 or 25mfd part.

The voltage rating of the new caps MUST equal or exceed that of the original.
There's really no upper limit for new cap ratings, although no reason to go wild.

Modern caps are readily available from all electronic distributors, including:
Mouser Mouser Electronics - Electronic Components Distributor
Digi-Key DigiKey Electronics - Electronic Components Distributor
Newark Newark element14 | Electronic Components Distributor
Allied Allied Electronics - Industrial Automation & Control Products Distributor

These places generally have no minimum order, and charge only actual shipping cost.

- Leigh

Thanks for the responses.

I know about the zero-adjust (the meter has to be removed from the back of the front panel to access the adjustment screw). There is no access hole behind the bezel.

The unit was sitting for many years before I turned it on today. At this time the meter is not functioning in any range but the +- lights do respond to the probe.

Before I take it apart, I'll wait to see if anyone has worked on this particular model before.

Thanks,

Bill

I have a very similar unit. If the three lights respond to the probe displacement, the device is probably working OK with only the meter stuck. This is usually caused ether by a tiny steel cutting caught in the meter magnet and blocking the coil movement. Can be carefully removed with tweezers once the meter is opened. I had this problem and it is common in a machine shop where ferrous metals are machined.
The other cause of stuck meter can be the result of impact. Often this tangles the hair-spring. This too is easy to fix.
Broken pivots, dead meter coil, etc. are difficult to repair. Might be easier to replace the meter itself. Most are 100 or 250 micro-amp meters. You can find an inexpensive (or free) old meter and fit it in the instrument. The term is "Panel Meter".
Good luck!

When the power is OFF and input probes disconnected, does the needle move when the unit is rocked from side to side?

BTW, I recommend removing foreign objects that get lodged between the armature and magnet by using a narrow strip of cellophane tape held with a pair of tweezers. The tape will go into places the tweezers can't, is not attracted by the magnet and is less likely to cause damage.

billzweig said:

I have a very similar unit. If the three lights respond to the probe displacement, the device is probably working OK with only the meter stuck. This is usually caused ether by a tiny steel cutting caught in the meter magnet and blocking the coil movement. Can be carefully removed with tweezers once the meter is opened. I had this problem and it is common in a machine shop where ferrous metals are machined.
The other cause of stuck meter can be the result of impact. Often this tangles the hair-spring. This too is easy to fix.
Broken pivots, dead meter coil, etc. are difficult to repair. Might be easier to replace the meter itself. Most are 100 or 250 micro-amp meters. You can find an inexpensive (or free) old meter and fit it in the instrument. The term is "Panel Meter".
Good luck!

View attachment 141109

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Thanks for the info. I'll dig around in it this week.

Bill

niemi24s said:

When the power is OFF and input probes disconnected, does the needle move when the unit is rocked from side to side?

BTW, I recommend removing foreign objects that get lodged between the armature and magnet by using a narrow strip of cellophane tape held with a pair of tweezers. The tape will go into places the tweezers can't, is not attracted by the magnet and is less likely to cause damage.

Click to expand...

The needle has moved from handling the unit. It was closer to zero when I first got it.

Bill

Bill in PA said:

The needle has moved from handling the unit. It was closer to zero when I first got it.

Bill

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Looks that it is a metal sliver in the the meter coil path. I've fixed dozens of meters with this kind of a problem. Yes, cellophane tape (as niemi24s suggested) or piece of masking tape do work well for removing smaller slivers that are too small/deep to reach with tweezers. By the way, when you open the meter movement do it away from the shop and on a very clean and dust free bench. It is best to seal the meter bezel when the repair is done and the meter movement reassembled. I melt a little bit of paraffin, asphaltum or beeswax in an aluminium foil muffin pan and paint the hot liquid on the seam of the closed bezel/case joint. Never had those meter fail again (so far for up to 45 years )
One more thing - make sure the meter glass is fully cemented to the bezel. If gaps are seen or the glass is loose, fix before reassembly.

Bill in PA said:

The needle has moved from handling the unit. It was closer to zero when I first got it.

Click to expand...

That's an indication the meter movement is binding somewhere: needle rubbing on scale; foreign material between armature and central or peripheral magnet poles; or a tangled (overlapped) spring as BillZweig suggested.

Time to pull the meter, remove its clear cover plate (in a dust-free environment) and peek inside.

I would strongly recommend referring this to a qualified meter repair shop.

Microammeters are very delicate instruments.
It's easy to screw up the springs and mess up the calibration without knowing it.

- Leigh

I finally got back to this unit. The coil/needle assembly was binding with poor continuity between the needle and ground. I fiddled with it for a couple of hours, but could not get it to work smoothly. It is nerve-racking because it is so delicate.

I googled "center zero moving coil dc voltmeter" for a replacement, but I could not find a DC meter that reads -1.5V - 0 - +1.5V.

The original is made by Sifam (England). I may contact them and they do have a US distributor. I was hoping for something easily found off-the-shelf.

Unfortunately, I am stupid when it comes to this stuff.

Bill

Purchased a new meter back in June from Sifam Tinsley. About $65.00 including shipping from the UK. I did not expect it would be that inexpensive.

Bill